When does a public charging membership actually pay for itself?
A charging subscription pays off only when the saving on energy exceeds the fee. For an illustrative monthly fee of 10 and a discount of 0.10 per kWh, the energy-only break-even point is 100 kWh on that tariff. Below that amount, the fee costs more than the energy discount saves.
Use the energy you will actually buy through the offer. Charging at home or on another network does not contribute to that discount. Include connection, parking and other applicable charges in a separate total.
The tariff comparison tool can help with the arithmetic. Replace every example price with the current offer you can use.